This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Proteasome component S5a is a ubiquitin receptor, and it plays important roles in protein degradation pathway. The function profile of S5a is expected to be elucidated by using modern NMR techniques.